Prevention of global warming has been an urgent issue in recent years, and all the aspects of society are requested to achieve power saving due to this reason. For example, an enormous amount of electric power is consumed for air conditioning in a factory, a large office building, an Internet data center or the like (hereinafter referred to as a “facility such as an office building”) and there are demands for both of power saving in such air-conditioning equipment and optimization of air conditioning.
In order to optimize air conditioning in a facility such as an office building, it is preferable to measure temperatures and wind velocities in many positions in the facility and to control air-conditioning equipment based on measurement results. When there are few measurement positions, temperature sensors and wind velocity sensors may be individually installed in the respective positions. The temperature sensor usable for this purpose may be a thermocouple, a platinum resistance temperature detector, a thermistor, an expansion thermometer, and the like. Meanwhile, the wind velocity sensor usable may be a hot-wire wind velocity sensor, a vane (windmill) type wind velocity sensor, an ultrasonic wind velocity sensor, and the like.
However, when the aforementioned sensors are used in many measurement positions, a large number of sensors are used, which leads to an increase in cost of the entire system. In the meantime, an increase in the number of sensors leads to an increase in cost required for maintenance. In this regard, there is a proposal to measure a temperature in a facility such as an office building by use of a temperature measurement device employing an optical fiber as a temperature sensor (such a device will be hereinafter referred to as an “optical fiber temperature measurement device”).
The optical fiber temperature measurement device is configured to measure a temperature by inputting a laser beam into an optical fiber and detecting Raman backscattered light generated inside the optical fiber. The device may measure temperature distribution in a longitudinal direction of the optical fiber within a short time. Meanwhile, there is also a proposal of a flow velocity measurement device which employs an optical fiber as a flow velocity sensor. This flow velocity measurement device is configured to heat an optical fiber with a heating element and to calculate a flow velocity of a fluid based on a change in temperature. A wind velocity in a facility such as an office building may be measured by use of the flow velocity measurement device of this type.
Patent Document 1: Japanese Laid-open Patent Publication No. 05-107121
Patent Document 2: Japanese Laid-open Patent Publication No. 06-174561